Load-break disconnect with pivotal fuses having pivotal support means



Jan. 4, 1966 w s. EDSALL 3,227,843

LOAD-BREAK DISONNEGT WITH PIVOTAL FUSES HAVING PIVOTAL SUPPORT MEANS Filed Oct. 18, 1963 5 Sheets-Sheet 1 1N VEN TOR. William S. Edsull Fig.2 W

Jan. 4, 1966 w s, Ds 3,227,843

LOAD-BREAK DISONNECT WITH PIVOTAL FUSES HAVING PIVOTAL SUPPORT MEANS Filed Oct. 18, 1963 3 Sheets-Sheet 2 V OFF By Jan. 4, 1966 w s. EDSALL 3,

LOAD-BREAK DISONNECT WITH PIVOTAL FUSES HAVING PIVOTAL SUPPORT MEANS Flled Oct. 18, 1963 5 SheetsSheet 5 F 'ig 7 g.

0 4e 23 48 so 29 4e Fi g. I O

INVENTOR 45 William S. Edsull 2.2 4! 42 fig 35 26 29 47 44 MMM/ United States Patent 3,227,843 LOAD-BREAK DISCONNECT WITH PIVOTAL USES HAVING PIVOTAL SUPPORT MEANS William S. Erlsall, Boston, Mass, assignor to The Chase- Shawmut Company, Newburyport, Mass. Filed Get. 18, 1963, Ser. No. 317,249 6 Claims. (Cl. 200114) This invention has reference to load-break switches, or load-break disconnects, which are capable of interrupting major fault currents, or short-circuit currents.

It is one object of this invention to provide improved load-break switches, or load-break disconnects, which are backed-up by fuses, and more particularly current-limiting fuses.

Another object of this invention is to provide extremely compact combinations of load-break switches or loadbreak disconnects and back-up fuses therefor.

A further object of this invention is to provide combinations of load-break switches and back-up fuses for the latter which combinations are very compact as a result of using the contacts of the fuses as movable switch contacts and of pivoting the fuses around the longitudinal axes thereof to achieve opening and closing operations of an electric polyphase circuit.

Another object of this invention is to provide multipolar load-break switches, or load-break disconnects, including electric fuses movable relative to pairs of fixed contacts and including operating means for imparting a pivotal motion to the fuses about the axes thereof, said operating means being segregated from the fuses and arranged adjacent to one of the ends of a group of fuses.

A still further object of this invention is to provide load-break switches, or load-break disconnects, including a plurality of fuses wherein each fuse is pivotable about the longitudinal axis thereof, and wherein this pivotal motion of each of said plurality of fuses is achieved by a common fuse-operating mechanism.

A further object of this invention is to provide loadbreak switches, or load-break disconnects, including backup fuses wherein the are drawn incident to interruption of load currents and of overload currents are extinguished by novel and improved arc-quenching means.

These and other objects of my invention and advantages thereof will become apparent from the following description of the invention taken in connection with the accompanying drawings in which:

FIG. 1 is an isometric view of a structure diagrammatically illustrating the invention;

FIG. 2 shows the same structure as FIG. 1 and in the same fashion as FIG. 1 but in another position;

FIG. 3 is is a front elevation of an operating mechanism for the structure shown in FIGS. 1 and 2;

FIG. 4 is a side elevation of the structure shown in FIG. 3 seen in the direction of the arrow R of FIG. 3;

FIG. 5 is a top plan view of the structure of FIG. 3;

FIG. 6 is a diagrammatic representation of another operating mechanism for the structure of FIGS. 1 and 2;

FIG. 7 is mainly a front elevation of a portion of a load-break disconnect embodying the present invention;

FIG. 8 is a vertical section of the structure of FIG. 7 mainly along 88 of FIG. 7;

FIG. 9 is a horizontal section of the structure of FIG. 7 mainly along 99 of FIG. 7, and

FIG. 10 shows a detail of the structure of FIGS. 710 taken along 1010 of FIG. 9.

Referring now to the drawings, and more particularly to FIGS. 1 and 2 thereof, reference character 1 has been applied to indicate three current-limiting fuses of which each is provided with a pair of contacts 2 projecting radially outward from the casing of each particular fuse.

3,227,843 Patented Jan. 4, 1966 The internal structure of the fuses 1 has not been shown in any of the figures of the drawings. It may be of a more or less conventional nature as shown, for instance, in US. Patent 2,794,883 to Frederick J. Kozacka, Fuse Contact Structures, June 4, 1957. Fuse contacts 2 are adapted to cooperatively engage pairs of fixed contacts 3. Each pair of fixed contacts 3 is arranged in the circuit of one phase of a polyphase circuit U, V, W. The current path of each fuse 1 includes a pair of terminals 4. According to FIG. 1 fuse contacts 2 are in engagement with the fixed contacts 3. Hence the current path of each phase comprises upper terminal 4, upper fixed contact 3, upper movable fuse contact 2, the fusible elements inside of the fuse (not shown), lower rnovable fuse contact 2, lower fixed contact 3, and lower terminal 4. Each fuse 1 has a vertical axis of symmetry and each fuse is adapted to be pivoted in counterclockwise direction about its aforementioned axis. In other words, fuses 1 are adapted to be pivoted from their positions shown in FIG. 1 wherein contacts 2 engage contacts 3 to their positions shown in FIG. 2 wherein contacts 2 are out of engagement with contacts 3. The arrows S in FIG. 2 indicate the sense of pivotal motion of fuses 1 when pivoted from their circuit closed positions shown in FIG. 1 to their circuit open positions shown in FIG. 2. When moving from their circuit closed positions shown in FIG. 1 to their circuit open positions shown in FIG. 2 an arc is drawn between each cooperating pair of parting contacts 2, 3. If this are is of overload current magnitude, e.g. two or three times the rated current of fuses 1, the overload current are must be extinguished by effective overload interrupting means. FIGS. 7-10 and in particular FIGS. 9 and 10 show a way in which this can readily be achieved.

The means for operating fuses 1 in the aforementioned manner have been deleted in FIGS. 1 and 2. Such means are illustrated diagrammatically in FIGS. 36.

Referring now to FIGS. 35, reference character 1 has been applied to indicate a fuse pivotable about the vertical axis of symmetry thereof. Fuse 1 may be one of a set of three fuses such as shown in FIGS. 1 and 2. Fuse 1 is integral with a gear sector 1b in meshing engagement with a rack 5. Rack 5' is provided with a pin 6' engaging a helical slot 7 in a drum 8 pivotable about shaft 9'. Drum 8' is pivotable by means of handle 10 under the action of overcenter spring 11. The latter has been omitted in FIGS. 3 and 5 but has been clearly shown in FIG. 4. Handle 10' may be moved to two limit positions of which one has been shown in FIGS. 35. These two limit positions of handle 10', grooved drum 8', pin 6, rack 5 and one or more fuses 1 are determined by a pair of dogs or stops 12'. If handle 10' is turned in counterclockwise direction as seen in FIG. 4 out of engagement with the upper stop or dog 12 and into engagement with the lower stop or dog 12, rack 5' is moved from the right limit position shown in FIG. 3 to the left limit position thereof. Thus causes a counterclockwise pivotal motion, as seen in FIG. 5, of one or more fuses 1. Such pivotal motion causes separation of movable fuse contacts 2 from fixed contacts 3 and thus interruption of the circuit into which fuse 1' is included. It will be apparent that the upper limit position of handle .10 shown in FIG. 4 is the ON or circuit closed position. The lower limit position of handle 10 which is assumed by the latter when pivoted about degrees into engagement with the lower dog or abutment 12 is the OFF or circuit closed position. As a general rule the fixed contact 3' ought to be arranged laterally of the fuse structure so that when the movable fuse contacts 2 are moved out of engagement with the fixed contacts 3, the former are moved forwardly to clearly visible positions, thus making it readily apparent that the circuit under control of the load-break disconnect is interrupted.

In FIG. 6 the fuse 1" is shown in the OFF position, its fuse contacts 2" being the in front plane. Fuse 1 is pivotable about the longitudinal axis thereof by means of a linkage 13', 14" operable by a handle 15" pivotable about fulcrum 16" and being under the action of overcenter spring 17". If handle 15" is pivoted in clockwise direction about fulcrum 16 link 13" is moved from its position shown in solid lines to its position shown in dotted lines. As a result, fuse 1 and its contacts 2 are pivoted in clockwise direction about 90 degrees from the limit position wherein contacts 2 are in front of the structure to the limit position wherein contacts 2" are on the side of the structure. In that position fuse contacts 2" may engage cooperating fixed contacts (not shown in FIG. 6).

It will be apparent to anyone skilled in the art that FIGS. 36 are diagrammatic representaitions of conventional commercial over-center spring operating mechanims as used in many switching devices and circuit breakers. Since such operating mechanisms are well known in the art the same have been indicated in a relatively diagrammatic fashion omitting auxiliary parts which are not essential to an understanding of the structure embodying the present invention, but may be essential for achieving smooth and satisfactory opening and closing of pairs of cooperating contacts by a snap action.

Referring now to FIGS. 79, numeral 23 has been applied to indicate a base of insulating material, preferably a molded insulating material. Base 20 is subdivided by partitions to form a plurality of chambers or compartments 22. FIGS. 7 and 9 show one such chamber or compartment 22 in full, and also portions of two adjacent chambers or compartments 22. The number of such chambers or compartments must be at least equal to the number of fuses to be accommodated. This number may be exceeded by one, in which case the additional chamber or compartment may be used to house the operating mechanism common to all fuses, i.e. an operating mechanism of the kind diagrammatically illustrated in FIGS. 36. Arranged in the median plane of each compartment is a pair of terminal elements 23 adapted to clamp therein one end of a cable (not shown). Each terminal element 23 is mounted on a metal strap 24. The ends of metal straps 24 remote from terminal elements 23 support fixed contacts 25. Each pair of fixed contacts 25 is adapted to be engaged by a pair of movable contacts 26 integral with an electric fuse and projecting radially outwardly from the cylindrical casing 27 thereof. Bases 20 defines a platform 28 extending through all compartments 22 thereof intended for accommodating an electric fuse. Platform 28 defines a slot 29 in each of compartments 22 and each such slot 29 is occupied by a slide 30 which has a pin-shaped projection 31 on the upper surface thereof. Pin-shaped projection 31 extends into a similarly shaped recess in a fuse carrier or fuse support 32. The latter comprises a cylindrical lateral wall 33 and a bottom or fuse-supporting platform 34. Lateral wall 33 is provided with a slot 35 extending parallel to the axis of wall 33 and the movable contacts 26 project from the space inside wall 33 through slot 25 to space outside wall 33. Bottom or fusesupporting platform 34 supports a fuse accommodated inside fuse carrier or fuse support 32. Wall 33 of carrier 32 is wrapped around the casing 27 of the fuse accommodated in carrier 32. Each compartment 22 is subdivided by a horizontal partition 36 having a circular cut-out 37. Circular cut-out 37 guides the upper portion of wall 33 of support 32, while its lower portion is guided by pin 31 projecting into bottom or platform 34. The outer surface of wall 33 is provided with a gear sector 38 in meshing engagement with rack 39 guided in groove 20a formed in the rear wall of base 20. Rack 39 may be operated by an operating mechanism of the kind shown in FIGS. 35 and described in connection therewith. As an alternative, link 14 of FIG. 6 and the operating mechanism associated with it may be substituted for rack 39. In the position of the parts shown in FIGS. 79 the circuit is interrupted. Moving rack 39 from left to right as seen in FIGS. 7 and 9 results in clockwise pivotal motion of fuse supports 32 and of the fuses supported by the latter. By virtue of this motion fuse contacts 26 are moved from their positions shown in FIGS. 7 and 9 into engagement with fixed contacts 25. This establishes the following current path: Upper terminal 23, upper strap 24, upper fixed contact 25, upper fuse contact 26, internal fuse structure (not shown), lower fuse contact 26, lower fixed contact 25, lower strap 24, lower terminal 23.

A movement of rack 39 in the direction from right to left, as seen in FIGS. 7 and 9, results in a counterclockwise pivotal motion of fuse supports 32 and of the fuses supported by the latter and of the fuse contacts 26 forming an integral part of the fuses. Hence contacts 26 part from contacts 25 with which they were engaged heretofore. The arcs formed by parting of contacts 25 and 26 are quenched by arc-chutes generally indicated by reference character 40 in FIG. 9 and omitted in FIGS. 7 and 8. Are chutes 40 comprise an angularly shaped plate-support 41 of insulating material, e.g. hard fiber. Plate supports 41 support a plurality of arc-quenching plates 42 of iron or another magnetizable material. Plates 42 are arranged in spaced relation and form a stack the constituent plates of which converge toward the common axis of the fuse and its support 32. Arc-quenching plates 42 are provided with slots in the shape of an inverted V to which slots reference character 43 has been applied. The arcs formed between parting contacts 25, 26 is drawn by magnetic action into the wide open ends of slots 43 and thus the arcs are elongated and the arc voltage is increased concomitantly. Plates 42 are coated with a synthetic resin evolving gases when under the heat of an electric arc. Thus the arcs drawn into slots 43 never get into physical engagement with the metal plates 42 and cannot vaporize the metal of which plates 42 are made, e.g. iron. The gases evolved from plates 42 form streams or jets turbulently mixing the hot products of arcing with relatively cool unionized gas and thus greatly accelerating the dielectric recovery of the arc gaps formed between the separated contacts 25 and 26.

Base 20 is covered by a hood 44 having partitions 45 abutting against the partitions 21 of base 20. Hood 44 is open at the top, thus allowing free venting of products of arcing formed upon separation of cooperating contacts 25, 26. The bottom 46 of hood 44 abuttingly engages platform 28 of base 20. The front panel of hood 44 defines a wide slot or cut-out 47 exposing to view the front portion of fuse support 32 and its slot 35 and the fuse contacts 26 projecting radially outwardly from the casing 27 of the fuse through slot 35. Thus it is always readily apparent whether or not the circuit which is controlled by the load-break disconnect is open or closed, even though hood 44 is in position and covers a large portion of the structure of the load-break disconnect.

Reference numeral 48 has been applied to indicate reinforcement fins integral with base 20 situated below platform 28.

It will be apparent from FIGS. 7 and 8 that terminals 23 are arranged outside of hood 44, i.e. above hood 44 and below hood 44. Thus there is no need to remove hood 44 for connecting the load-break disconnect into an electric circuit. Hood 44 needs only to be removed from base 20 when it is desired to inspect the fixed contacts 25, or for similar maintenance operations. The replacement of blown fuses does not require a removal of hood 44 from base 20. Following blowing of one or more fuses contacts 26 are separated from contacts 25, i.e. all the parts of the load-break disconnect are moved to the positions thereof shown in FIGS. 79. Now the fuses may readily be lifted out of their supports 32 and replaced by new fuses, i.e. fuses which have not blown and whose fusible elements are intact and able to carry electric current. Removal of blown fuses may be achieved by placing a screw-driver under one of the fuse contacts 26 and applying an upward pressure against the respective contact whereby the fuse is lifted out of its support 32 and can be grasped manually.

Hood 44 may be screwed against base 20 by screws not shown. Openings for insertion of such screws have been shown in FIG. 7 and indicated by reference character 49.

It will be apparent from the foregoing that fuse contacts 26 are aligned along a generatrix of casing 27. Contacts 26 project transversely through casing 27, i.e. from the outside thereof into the inside thereof, the drawings showing only the portions of contacts 26 situated outside of casing 27.

According to FIGS. 7-9 terminal elements 23 define a plane at right angles to the general plane of base 20, or to the rear plate of the base. The fuse in front of terminals 23, and in particular said casing 27 thereof, is bi-sected by the aforementioned plane at right angles to the general plane of the base 20.

One arc-chute 40 is arranged in the circular path of upper fuse contact 26 and another arc-chute 40 is arranged in the circular path of the lower fuse contact 26. Both these arc-chutes are identical and their distance in vertical direction is substantially equal to the spacing between fixed contacts 25, or to the length of longitudinal slot 35 in the lateral wall 33 of fuse carrier 32.

It will further be apparent from FIGS. 79 that fuse support or fuse carrier 32 is arranged in such a fashion that the longitudinal axis thereof is parallel to the general plane of, or defined by, base 20.

In the foregoing I have described my invention solely in connection with illustrative specific embodiments thereof. Since many variations and modifications will now be obvious to those skilled in the art, I prefer to be bound not by the specific disclosure herein contained but only by the appended claims.

I claim as my invention:

1. A polyphase l0ad-break disconnect comprising in combination:

(a) a plurality of fuses each including a cylindrical insulating casing and each including a pair of fuse contacts aligned along a generatrix of said casing and projecting at right angles across said casing;

(b) a plurality of fuse supports each arranged in coaxial relation to one of said plurality of fuses and each comprising a fuse-supporting platform supporting one of said plurality of fuses and having pivoting means on the lower side thereof, each of said plurality of fuse supports further comprising a lateral wall defining a longitudinal slot for the passage of said pair of fuse contacts of one of said plurality of fuses;

(0) common tandem operating means for said plurality of fuses including a handle for imparting to each of said plurality of fuse supports a pivotal motion about said pivoting means;

(d) a plurality of pairs of fixed contacts each arranged along a straight line parallel to the axis of pivotal motion of one of said plurality of fuse supports and each arranged in the path of the pivotal motion of a pair of said fuse contacts of one of said plurality of fuses; and

(e) a plurality of arc-chutes each arranged in the path of said pivotal motion of one of said pair of fuse contacts of one of said plurality of fuses.

2. A load break disconnect comprising in combination:

(a) a base;

(b) a plurality of pairs of spaced terminal elements arranged on and supported by said base adjacent edges thereof;

(c) a plurality of fuse supports arranged in a space bounded by said plurality of pairs of terminals and supported by said base, each of said plurality of fuse supports being open at the top end having a cylindrical lateral wall defining a longitudinal slot extending downward from said open top thereof, and each of said plurality of fuse supports having a pivot means at the closed bottom thereof for imparting a pivotal motion of each of said plurality of fuse supports about the axis of said cylindrical lateral wall thereof;

(d) common tandem operating means for said plurality of fuse supports including a handle for imparting a pivotal motion to each of said plurality of fuse supports about said axis of said cylindrical lateral wall thereof for moving each of said plurality of fuse supports selectively to two limit positions;

(e) a plurality of pairs of fixed contacts each pair of said plurality of pairs of fixed contacts being conductively connected to one of said plurality of pairs of terminals arranged and in registry along a straight line parallel to said axis of said lateral wall of one of said plurality of fuses; and

(f) a hood covering but a portion of said base, said hood having a plurality of longitudinal slots each exposing to view said longitudinal slot in one of said plurality of fuse supports when said one of said plurality of fuse supports is in one of said two limit positions thereof to expose to view contacts of fuses projecting out of said longitudinal slot in any of said plurality of fuse supports.

3. A load-break disconnect comprising in combination:

(a) a vertical base of insulating material defining a vertical plane and supporting partitions subdividing the space in front of said base into a plurality of chambers;

(b) a plurality of fuse supports each arranged in one of said plurality of chambers and each supporting a fuse comprising a casing having a vertical axis, and including a pair of fuse contacts projecting at right angles outward from the surface of said casing, and each of said plurality of fuse supports having a pivot means coextensive with said vertical axis of said casing of said fuse;

(c) common tandem operating means for said plurality of fuse support including a handle for imparting to each of said plurality of fuse supports a pivoting motion about said vertical axis of said casing of said fuse to move said pair of fuse contacts thereof selectively to a first limit position wherein said pair of fuse contacts is situated in a first plane substantially at right angles to said vertical plane defined by said base and to a second limit position wherein said pair of fuse contacts is situated in a second plane enclosing an angle with said first plane;

(d) a plurality of pairs of fixed contacts, each pair of said plurality of pairs of contacts being aligned along a straight line parallel to said vertical plane defined by said base and each arranged in one of said plurality of chambers, each of said plurality of pairs of fixed contacts being arranged in the paths of pivotal motion of said pair of fuse contacts of a fuse supported by each of said plurality of fuse supports; and

(e) arc-quenching means arranged along said paths of motion of said pair of fuse contacts of each fuse supported by one of said plurality of fuse supports between said first limit position of said fuse contacts and said second limit position of said fuse contacts.

4. A polyphase load-break disconnect comprising in combination (a) a plurality of fuses each including a vertically arranged tubular casing and each including a pair of fuse contacts having a predetermined axial spacing and projecting at right angles outward from the surface of said casing;

(b) a plurality of substantially tubular fuse supports each open at the top thereof to allow insertion of the casing of one of said plurality of fuses into each of said plurality of fuse supports from said top thereof and each of said plurality of fuse supports being closed at the bottom thereof to support on said bottom the casing of one of said plurality of fuses, and the side wall of each of said plurality of fuse supports defining a slot extending from said open top in longitudinal direction allowing said pair of fuse contacts of one of said plurality of fuses to project from the inside of each of said plurality of fuse supports to the outside thereof;

(c) a common base supporting said plurality of fuse supports;

(d) a plurality of pivot means supported by said common base each coaxial with one of said plurality of fuses and each supporting one of said plurality of fuse supports;

(e) common tandem operating means for said plurality of fuse supports for imparting to each of said plurality of fuses a pivotal motion about one of said plurality of pivot means;

(f) a plurality of pairs of fixed contacts supported by said common base, each pair of said plurality of pairs of fixed contacts being arranged along a straight line parallel to said plurality of pivot means to be selectively engaged by, and separated from, said pair of fuse contacts of one of said plurality of fuses upon pivotal motion of said plurality of fuse supports; and

(g) a plurality of pairs of arc-quenching means supported by said common base, each pair of said plurality of pairs of arc-quenching means having a spacing substantial equal to said predetermined axial spacing of said pair of fuse contacts of each of said plurality of fuses and each pair of said plurality of pairs of arc-quenching means being arranged in the path of the motion of said pair of fuse contacts of one of said plurality of fuses.

5. A polyphase load-break disconnect comprising in combination:

(a) a plurality of fuses each including a cylindrical insulating casing and each including a pair of fuse contacts aligned along a generatrix of said casing, having a predetermined axial spacing and projecting at right angles transversely across said casing;

(b) a plurality of substantially tubular fuse supports each open at the top thereof to allow insertion of the casing of one of said plurality of fuses into each of said plurality of fuse supports from said top thereof and each of said plurality of fuse supports being closed at the bottom thereof to support on said bottom the casing of one of said plurality of fuses, and the side wall of each of said plurality of fuse supports defining a slot extending from said open top in longitudinal direction allowing said pair of fuse contacts of one of said plurality of fuses to project from the inside of each of said plurality of fuse supports to the outside thereof;

(c) a common base supporting said plurality of fuse supports;

(d) a plurality of pivot means supported by said common base each coaxial with one of said plurality of fuses and each supporting one of said plurality of fuse supports;

(e) common tandem operating means for said plurality of fuse supports for imparting to each of said plurality of fuses a pivotal motion about one of said plurality of pivot means;

(f) a plurality of pairs of fixed contacts supported by said common base, each pair of said plurality of pairs of fixed contacts being arranged along a straight line parallel to a generatrix of said casing of one of said plurality of fuses and each arranged in the path of the pivotal motion of said pair of fuse contacts of one of said plurality of fuses; and

(g) a plurality of pairs of stacks of spaced arc-quenching metal plates, each pair of said plurality of pairs of stacks being arranged transversely to the path of said pivotal motion of said pair of fuse contacts of one of said plurality of fuses, and the constitutent metal plates of said plurality of stacks having a synthetic resin coating on the outer arc-exposed surfaces thereof to evolve gases when subjected to the heat of an electric arc.

6. A polyphase load-break disconnect comprising in combination:

(a) a frame structure of insulating material having a plurality of partitions sub-dividing said frame structure into a plurality of compartments each open at the front and at the top thereof;

(b) a plurality of fuses each including an insulating casing and each including a pair of fuse contacts projecting at right angles outward from the surface of said casing, each of said plurality of fuses being arranged in one of said plurality of compartments;

(0) a plurality of fuse supports each arranged in coaxial relation to one of said plurality of fuses in one of said plurality of compartments and housing one of said plurality of fuses in the inside thereof, each of said plurality of fuse supports being open at the top thereof and having a lateral wall defining a longitudinal slot for the passage of said pair of fuse contacts of one of said plurality of fuses, said longitudinal slot extending downwardly from the open top of each of said plurality of fuse supports, and each of said plurality of fuse supports being pivotable about the longitudinal axis thereof to two limit positions and having pivot means at the end remote from said open top thereof;

(d) common tandem operating means for said plurality of fuse supports supported by said frame structure;

'(e) a plurality of pairs of fixed contacts, each pair of said plurality of pairs being arranged adjacent the path of movement of said pair of fuse contacts of one of said plurality of fuses when pivoted jointly with one of said plurality of fuse supports to be selectively engaged by, and separated from, a pair of said fuse contacts of one of said plurality of fuses;

(f) a plurality of pairs of arc-chutes, each pair of said plurality of pairs of arc-chutes being arranged in the path of one of said pair of fuse contacts of one of said plurality of fuses; and

(g) a hood of insulating material supported by said frame structure and having a plurality of partitions each abutting against one of said plurality of partitions of said frame structure, said hood being open at the top and including a front panel defining a plurality of slots each arranged to register with said slot in one of said plurality of fuse supports when said one of said plurality of fuse supports is in one of said two limit positions thereof.

References (Iited by the Examiner UNITED STATES PATENTS 1,619,640 3/1927 Sloane 200129 1,907,266 5/1933 Mills 2001 14 1,914,129 6/1933 Jennings 200144 2,314,693 3/ 1943 Dickinson. 2,527,269 10/1950 Killian 200-144 2,911,505 11/1959 Legg et al. 200144 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

H. A. LEWITTER, Assistant Examiner. 

1. A POLYPHASE LOAD-BREAK DISCONNECT COMPRISING IN COMBINATION: (A) A PLURALITY OF FUSES EACH INCLUDING A CYLINDRICAL INSULATING CASING AND EACH INCLUDING A PAIR OF FUSE CONTACTS ALIGNED ALONG A GENERATRIX OF SAID CASING AND PROJECTING AT RIGHT ANGLES ACROSS SAID CASING; (B) A PLURALITY OF FUSE SUPPORTS EACH ARRANGED IN COAXIAL RELATION TO ONE OF SAID PLURALITY OF FUSES AND EACH COMPRISING A FUSE-SUPPORTING PLATFORM SUPPORTING ONE OF SAID PLURALITY OF FUSES AND HAVING PIVOTING MEANS ON THE LOWER SIDE THEREOF, EACH EACH OF SAID PLURALITY OF FUSE SUPPORTS FURTHER COMPRISING A LATERAL WALL DEFINING A LONDITUDINAL SLOT FOR THE PASSAGE OF SAID PAIR OF FUSE CONTACTS OF ONE OF SAID PLURALITY OF FUSES; (C) COMMON TANDEM OPERATING MEANS FOR SAID PLURALITY OF FUSES INCLUDING A HANDLE FOR IMPARTING TO EACH OF SAID PLURALITY OF FUSE SUPPORTS A PIVOTAL MOTION ABOUT SAID PIVOTING MEANS; (D) A PLURALITY OF PAIRS OF FIXED CONTACTS EACH ARRANGED ALONG A STRAIGHT LINE PARALLEL TO THE AXIS OF PIVOTAL MOTION OF ONE OF SAID PLURALITY OF FUSE SUPPORTS AND EACH ARRANGED IN THE PATH OF THE PIVOTAL MOTION OF A PAIR OF SAID FUSE CONTACTS OF ONE OF SAID PLURALITY OF FUSES; AND (E) A PLURALITY OF ARC-CHUTES EACH ARRANGED IN THE PATH OF SAID PIVOTAL MOTION OF ONE OF SAID PAIR OF FUSE CONTACTS OF ONE OF SAID PLURALITY OF FUSES. 